YanoSec
Progress0 of 152 lessons complete

Course / 02 Computers / Lesson 01 of 08

Hardware a security lesson will mention

Estimated time: 15 min reading · 15 min activity

Before running a practice computer inside your laptop, you need to check its resources. A laptop can have plenty of space for files but too little free memory for another operating system. This lesson helps you keep those limits separate.

Hardware means the physical parts of a computer. The CPU, or central processing unit, executes instructions. RAM, or random-access memory, holds data used by running programs. Storage keeps saved files, including after the power is off. An SSD, or solid-state drive, is one kind of storage.

The operating system (OS) manages programs, memory, files and devices. Windows, macOS and Ubuntu are examples. A virtual machine (VM) is a software-created computer that runs its own OS while using resources from your physical computer. We will look inside that arrangement later in this stage.

Before you begin

Recommended first
Where practice is allowed
Estimated time
15 min reading, 15 min activity. Setup and optional practice may take longer.
Where you work
Use a desktop or mobile browser with paper or a text editor for notes. No installation, account, terminal or paid service is needed. The cards describe fictional computers. Allow another 10–15 minutes if you choose the optional challenge.
Without a lab
Read the cards on this page and write your predictions on paper or in a text editor. Downloads contain the same text and are optional. Use the activity steps to explain your reasoning before comparing it with the expected result. Answer checking needs JavaScript and a secure browser context (HTTPS or a local preview). Saving progress also needs usable browser storage.

After this lesson you can:

  • Identify the roles of CPU, RAM and storage.
  • Calculate spare RAM and storage from a stated inventory.
  • Explain why a guest's architecture must match its setup route.

01Example

This fictional laptop has 8 GiB of RAM and 100 GiB of free storage. GiB is a unit of data size, explained below. A proposed VM receives 4 GiB of RAM and a virtual disk with a 30 GiB limit. Treat memory and storage as separate budgets. These planning calculations do not predict how smoothly it will run.

RAM: 8 GiB total - 4 GiB for the VM = 4 GiB left for other work
Storage: 100 GiB free - 30 GiB disk allowance = 70 GiB left

Other work includes the existing OS and applications.
The storage remainder must also cover downloads, updates and snapshots.

02Follow one document

Opening a document makes its data available to the editor. As you type, the new text may exist only in the editor's working data. Save writes the document to storage so it can be opened later. Closing an editor without saving can therefore lose changes even when an older saved file still exists.

Ordinary RAM loses its contents when power is removed. Some applications save automatically or offer recovery, but you need evidence that they have done so before relying on them. A backup is a separate recoverable copy of saved data.

The diagram is a starting model. Real computers also use caches, which keep frequently used data near the processor, and virtual memory, which can use storage to support memory management. These mechanisms do not make spare disk space the same as spare RAM, or turn an unsaved paragraph into a saved document.

Hardware roles: a simplified model
Storage --load instructions and data--> RAM
CPU --execute instructions using working data--> RAM
RAM --save file data--> Storage
OS: manages programs, memory, files and devices.

The CPU executes instructions. RAM holds active working data.
Ordinary RAM loses its contents when power is removed.
Storage retains saved files without continuous power.
Loading and saving move data between these roles.
Real computers also use caches and disk-backed virtual memory;
this model does not show every mechanism or physical connection.

Download the hardware roles diagram

03Read capacities and architecture

A byte is a unit of data size. A GiB is 1,073,741,824 bytes; a GB is 1,000,000,000 bytes. Check which unit a tool displays before comparing numbers. Installed RAM is the total memory fitted to the computer; currently available RAM is the amount available for more work. Likewise, a storage drive's total capacity differs from its free space.

A CPU core can execute instructions. A virtual CPU is a processor presented to a VM. Assigning virtual CPUs does not create more physical cores, and the existing OS still needs processing time.

CPU architecture is the family of instructions a processor uses, such as x86-64 or ARM64. An Ubuntu image labelled amd64 is for x86-64, including compatible Intel processors. Two systems being 64-bit does not establish that they use the same instruction family. Check the hypervisor's supported host and guest combination before installing.

RAM and storage are independent budgets: allocating 4 GiB RAM and 30 GiB disk allowance leaves 4 GiB RAM and 70 GiB storage.Model. A teaching model drawn by hand. It shows the idea, not real tool output.

Read the full explanation below.

CPU Executes instructions

RAM Active working data

Storage Saved data; downloads, updates and snapshots also need room. No performance prediction.

RAM for active working data

Allocated 0 GiB RAMRemaining 8 GiB RAM
0 GiB RAM4 GiB RAM

Free storage for saved data

Allocated 0 GiB storageRemaining 100 GiB storage
0 GiB storage30 GiB storage

Start with 8 GiB RAM and 100 GiB free storage; budgets cannot be exchanged.

Follow the explanation

  1. Start with 8 GiB RAM and 100 GiB free storage; budgets cannot be exchanged.
  2. 8 − 4 = 4 GiB RAM remains for the existing OS and applications.
  3. 100 − 30 = 70 GiB storage remains; that space must also cover other storage needs.
  4. Storage can be allocated independently: 70 GiB storage and all 8 GiB RAM remain in this model.
Read every state and value

1. Start with 8 GiB RAM and 100 GiB free storage; budgets cannot be exchanged.

Allocations
Resource: ram; Value: 0 · Resource: disk; Value: 0
Selected Resource
ram

2. 8 − 4 = 4 GiB RAM remains for the existing OS and applications.

Allocations
Resource: ram; Value: 4 · Resource: disk; Value: 0
Selected Resource
ram

3. 100 − 30 = 70 GiB storage remains; that space must also cover other storage needs.

Allocations
Resource: ram; Value: 4 · Resource: disk; Value: 30
Selected Resource
disk

4. Storage can be allocated independently: 70 GiB storage and all 8 GiB RAM remain in this model.

Allocations
Resource: ram; Value: 0 · Resource: disk; Value: 30
Selected Resource
disk
RAM and storage are independent budgets: allocating 4 GiB RAM and 30 GiB disk allowance leaves 4 GiB RAM and 70 GiB storage.

04Try a resource budget

Use this new inventory on paper. You do not need to inspect or change your device.

Hardware planning worksheet
Fictional inventories; no device was inspected.

Activity computer:
RAM installed: 16 GiB
RAM already in use: 7 GiB
Free storage: 120 GiB
CPU architecture: x86-64
Physical CPU cores: 4

Proposed practice guest:
RAM: 4 GiB
Virtual CPUs: 2
Virtual disk maximum: 30 GiB

Make separate RAM, CPU and storage rows in your notes.
Subtract existing use and guest RAM from installed RAM.
Subtract the disk maximum from free storage as a planning allowance.
Allow more storage for the downloaded installer image and snapshots.
Explain why spare disk space cannot be counted as spare RAM.
These values are an arithmetic exercise, not a performance guarantee.

Separate question case:
An editor holds an unsaved paragraph as active working data.
The saved document is a separate file on persistent disk storage.
Which resource holds the active working data in the lesson's model?
Answer format: RAM or disk storage.

Download the hardware planning worksheet

  1. Make separate rows for RAM, CPU and storage. Copy the activity computer's figures and the proposed VM allocations. Keep installed RAM, RAM already in use and free storage in their own columns.
  2. Calculate remaining RAM: subtract the 7 GiB already used and the proposed 4 GiB from the installed 16 GiB. Compare your result with the expected 5 GiB. This is a simplified budget; actual memory use changes over time.
  3. Reserve the proposed 30 GiB disk maximum from 120 GiB of free storage. Expected: 90 GiB before other downloads and snapshot growth. A virtual disk can grow gradually, but the physical drive must still have space when it grows.
  4. Record the proposed two virtual CPUs, four physical cores and x86-64 architecture. Explain why the host needs resources too. These numbers alone cannot establish adequate performance or compatibility.
  5. Finish with one fact you would check on a real host, such as currently available RAM or the vendor's supported OS list. Keep your note for setup. No settings changed during this activity.

05Optional challenge

Read your own device's About or System information without changing settings. Record the OS, architecture, installed RAM and free storage using the displayed units. Compare them with the worksheet. If settings are unavailable, compare a fictional second computer with 8 GiB RAM and 40 GiB free storage instead. Explain what more you would need to know before allocating a guest. Keep serial numbers and account names private.

06Fresh cases for the checks

Use these fictional cases for the checks below. They have different inputs from the worked examples. Read them here or make notes; no installation or external service is needed.

Hardware card A: three actions on a fictional computerOwned fixture. An original file made for this course. Follow the activity's instructions in your own lab.

A1: The processor carries out an editor instruction.
A2: An unsaved paragraph is active working data in the editor.
A3: A saved document remains available after power is off.
Use the lesson's starting model; no automatic save or recovery is established.

Hardware card B: a memory planning caseOwned fixture. An original file made for this course. Follow the activity's instructions in your own lab.

Installed RAM: 12 GiB
Reserve for the existing operating system and applications: 5 GiB RAM
Proposed guest allocation: 4 GiB RAM
Treat the reservation and guest allocation as separate parts of the installed total.
This simplified budget does not predict performance.

Hardware card C: an independent storage planning caseOwned fixture. An original file made for this course. Follow the activity's instructions in your own lab.

Drive capacity: 256 GiB
Currently free storage: 96 GiB
Reserve for the proposed guest disk: 29 GiB of that free storage
No other new storage reservations are included in this calculation.

Hardware card D: a fictional setup routeOwned fixture. An original file made for this course. Follow the activity's instructions in your own lab.

Host processor architecture: ARM64; the host is described as 64-bit.
Downloaded guest image label: Ubuntu amd64.
The proposed course setup route requires an x86-64 host and an amd64 guest image.
No alternative host/guest combination has been checked for this case.
The supplied text activity is available without installation.
These are the case's route requirements, not a current vendor support list.

07Explain your hardware decision

Optional self-check: write two or three sentences for someone who proposes increasing disk space to solve a shortage of RAM. Then explain why a 64-bit label alone cannot settle the architecture question.

Check your explanation: distinguish active working memory from saved-file storage; keep their budgets separate; identify the host and guest instruction families; and name the supported host/guest combination as something to check before setup. Do not claim that these planning figures prove good performance.

08Common mistakes

If a budget seems too generous, check whether you used total storage instead of free storage, or forgot existing RAM use. Recalculate one resource row at a time using matching units.

If storage is plentiful but available RAM is low, increasing the virtual disk will not solve the RAM shortage. Use the text route until a suitable memory budget is available.

If the host and image architecture differ, pause setup and check vendor support. Renaming an amd64 image does not convert it into an ARM64 image.

If a download fails, read the identical worksheet on the page and write your calculations in notes. You can finish this reasoning activity without a VM.

References